Electrical recording medium and process for recording thereon

ABSTRACT

The electrical recording medium comprises a composite mounted on a base sheet, said composite comprises an electron-donative color reactant, an electron-acceptive material and an electric conductive material, the electron-donative color reactant and the electron-acceptive m material being reacted thereby the color reactant coloring by itself, and said reaction brough about by multiplex effect of the electrolytic reaction and/or the exothermic reaction by applying the electric current. The recording process for recording on said electrical recording medium comprises the steps of mounting a composite comprising an electron-donative color reactant, an electron-acceptive material and an electric conductive material upon a base sheet, making a reaction between the electron-donative color reactant and the electron-acceptive material owing to an effect of or a multiplex effect of an electrolysis and/or an exothermic reaction, and thereby coloring the color reactant.

United States Patent [1 1 Sakata et al.

[ Nov. 13, 1973 ELECTRICAL RECORDING MEDIUM AND PROCESS FOR RECORDINGTHEREON [75] Inventors: Toshibumi Sakata; Noboru Yamato;

Fumio Fujimura; Tadasu Fukawa, all of Tokyo, Japan [73] Assignee: JujoPaper Co., Ltd., Tokyo, Japan [22] Filed: Dec. 27, 1971 [21] Appl. No.:212,263

[30] Foreign Application Priority Data Dec. 29, l970 Japan 45/126303Dec. 25, 1970 Japan 45/129299 [52} U.S. Cl. 204/2, 8/2, l17/36.8 [51]Int. Cl. B44m 5/00, B44m 5/20 [58] Field of Search 204/2; 8/2; l17/36.8

[56] References Cited UNITED STATES PATENTS 3,434,878 3/1969 Reis 204 23,518,038 6/1970 Spatz 204/2 Primary Examiner--T. TufarielloAttorney-George B. Oujevolk ABSTRACT The electrical recording mediumcomprises a composite mounted on a base sheet, said composite comprisesan electron-donative color reactant, an electronacceptive material andan electric conductive material, the electron-donative color reactantand the electron-acceptive m material being reacted thereby the colorreactant coloring by itself, and said reaction brough about by multiplexeffect of the electrolytic reaction and/or the exothermic reaction byapplying the electric current. The recording process for recording onsaid electrical recording medium comprises the steps of mounting acomposite comprising an electrondonative color reactant, anelectron-acceptive material and an electric conductive material upon abase sheet, making a reaction between the electrondonative colorreactant and the electron-acceptive material owing to an effect of or amultiplex effect of an electrolysis and/or an exothermic reaction, andthereby coloring the color reactant.

4 Claims, No Drawings ELECTRICAL RECORDING MEDIUM AND PROCESS FORRECORDING THEREON FIELD OF THE INVENTION This invention relates to anelectrical recording process which is adapted to gain coloring images byapplying an electric current and an electro-sensitive recording materialwhich is employed on the recording process.

PRIOR ART In the prior art, it is well known that there are tworecording process employing an application of electric current, such asan electrolysis recording process and discharge-breakdown recordingprocess.

The electrolysis recording process is carried out in such a manner asfollows:

1. introducing as ion from an electrode into a recording sheet,

2. discharging the ion above the electrode contacted with the recordingsheet, I

3. making an oxidation-reduction reaction on a surface of the electrodecontacted with the recording sheet,

4. making a'change of P H on the surface of the electrode contacted withthe recording sheet.

With reference to such recording sheet, various kinds of it have beenproposed already. The conventional recording sheets, however, have somedisadvantages. The recording sheets are needed to be wetted in arecording operation and the images recorded on the sheets react with anelectrolyte or the like to be discolored. In a recording operation orprocess of discharge-breakdown recording process, there are bad odor andsmoke due to electrical discharge, and at the same time the image is aptto be inferior in quality. Also a method for coloring or discoloring aheat sensitive material by means of electrical exothermic phenomena hasbeen invented. But, the coloring or discoloring method needs to beapplied to a special electro-conductive material.

It is well knownin prior art that an electron-donative color reactantfor example leuco compound and an electron-acceptive material is reactedso as to produce a visible colored image.

It is also well known that a thermal recording process comprising thesteps of dispersing an electron-donative color reactant and anelectron-acceptive material in a binder, making use of a visiblecoloring reaction, melting the electron-donative color reactant and/orthe electron-acceptive material by means of beating out of the outerheat source or infrared ray radiation, and reacting theelectron-donative I color reactant and the electronacceptive material so[as to color the color reactant. Further,.it is well known that leucocompound of an electron-donative color reactant, when it is electrolysedin an electrolyte solution, is'anodic oxidized on a surface of anelectrode to be colored.

We have examined and studied the'facts and knowledge mentioned above anddeveloped a recording process and an electro-sensitive recordingmaterial, wherein recordings are effected to gain visible colored imagesaccording to a multiplex effect of electrolysis and/or exothermicreaction of electric current, making use of electric signals.

The present invention essentially relates to an electrical recordingmedium comprising a composite mounted on a substrate or base sheet, saidbase sheet comprising an electron-donative color reactant, anelectronacceptive material and an electric-conductive material so as tocolor the color reactant by an electrolytic reaction of saidelectron-donative color reactant and electron-acceptive material occuredby applying of electric current or multiplex eddect of the electrolyticreaction and the exothermic reaction owing to the electric current and arecording or coloring process of said electrical recording medium.

The recording process of this invention will be still more fullydescribed hereinafter. When an electronacceptive material and anelectron-donative color reactant are electrolysed under the existence ofan electrolyte, both of them are reacted with each other and the colorreactant colores by itself. When to a composite comprising anelectron-acceptive material and an electron-donative color reactantmixed with an electric conductive material such as an electrolyte isapplied electric current statisfactorily, the electron-donative colorreactant or the electron-acceptive material is melted by the exothermicphenomena of electric current and reacted with each other in order tocolor the color reactant.

The present invention relates to an electrical recording mediumcomprising a composite mounted on a base sheet, said compositecomprising an electron-donative color reactant, an electron-acceptivematerial and an electron conductive material, the electron-donative andthe electron-acceptive material being reacted, thereby the colorreactant coloring by itself and said reaction brought about,-byelectrolysis itself and/or by multiplex effect of the electrolyticreaction and the exothermic reaction caused by applying the electriccurrent.

The present invention also relates to an electrical recording medium andto an electrolytic recording process, in which said recording mediumcomprising an electron-donative color reactant, an ele'ctron-acceptivematerial and an electrolyte, the electron-donative color reactant andthe electron-acceptive material being reacted, thereby the colorreactant coloring by itself and said reaction brought about by applyingthe electric current.

This invention further relates to an electric recording process, inwhich a composite mounted on a base sheet is used, said compositecomprising an electrondonative color reactant, an electron-acceptivematerial and electric conductive material, the color reactant coloringby itself and reaction brought about, by the electrolysis itself and/orby multiplex effect of the elec- 1 trolytic reaction and the exothermicreaction caused by applying the electric current.

The object of theis invention is to provide a new recording process anda recording medium, wherein the recording process is carried out toobtain visible co]- ored images of good quality by the use of anelectric Official Gazett of Japanese Patent Publication No.l4039/l970),or clay minerals of kaolin, acid-clay, silicic anhydride and aluminumoxide, etc.

The electric conductive materialsin the invention are variouselectrolytes having any electrical conductiveity in wet condition suchas watersoluble salts oflighium,sodium,potassium,zinc,magnesium,aluminum, or water solublepolyelectrolyte of alginate and polyacrylate, electrical conductivepolymer such as polymeric quaternary ammonium salt, antistatic agentssuch as anionic, cationic and non-ionic surface active agents, carbonblack, and semiconductive pigment such as partially reduced oxideofmetal or metal powder.

The steps of the process of this invention will be more fully pointedout below. One or a mixture of two or more of natural or syntheticpolymer such as polyvinyl alcohol, polyvinyl acetate, polyacrylic acidester, polystyrene,cellulose derivative, and synthetic rubber areprepared as a binder. Said electron-donative color reactant is addedinto the solution of the biner and powdered till the size of theparticle is fined down to 3 micron by means of a ball mill. The powderedreatant is mixed with the solution of the binder. The resultant iscalled hereinafter liquid A.

Then, an electron-acceptive material is added into the binder solution.The resultant solution is called hereinafter Liquid B. The Liquid A andB are mixed and an electro-conductive material is added to the mixtureto obtain coating color.

The liquid Cprepared according to said way is applied or impregnated onsuitable base sheet such as papers, fabrics, films or metal sheet, thendried for example in air the humidity of thereof being controlled so asto obtain electro-sensitive recording medium. Alternatively, a mixtureof liquid A and B may be impregnated on the base sheet and dried, andthen a electroconductive solution such as electrolyte maybe againapplied or impregnated on the base sheet. When the reaction occuringbetween the electron-donative color reactant and the electron-acceptivematerial is very active, and a smudging because becuse of coloringbefore the application of electric current and the preservating qualityis deteriorated, thereby it is effective that amine compound having adesensitizing function to'electronacceptive material such as cationicquaternary ammonium, polyamine or diamine is added, inhibiter, to theliquid B. To improve the tackiness upon a surface of theelectro-sensitive recording material, talc or the like is effectivelyemployed to mix with the liquid B.

When a voltage is impressed or applied on the electro-sensitiverecording material, an electric current easily runs through thecomposite comprising an electron-donative color reactant, anelectron-acceptive material and an electric conductive material, owingto the function of the electric conductive material. If theelectro-conductivity of the composite is low, it is necessary to raisethe voltage to be impressed. Thus the volume of the electric conductivematerial to be employed is appropriately determined. So as to drop thevoltage to be impressed or applied into readily applicable one.

It is preferable that said composite comprises an electrolyte so as toreact the electron-donative color reactant and the electron-acceptive'material by means of the application of electric current and thefunction of electrolysis and color the color reactant. Therefore, it

is desirable that said electrolyte is used as one of an electricconductive material. It is also desirable that an electric conductivematerial such as polyelectrolyte is employed in the binder. I

It is preferable thatthe base sheets have electroconductivity and aremade of papers, fabrics, plastics and films, electric conductivematerial being applied thereinto, or metal sheets, metal foils and metalevaporated sheets so as to improve the electro-conductivity of theelectro-sensitive recording medium.

Alternatively, it is possible that the base sheets are given an electricconductivity when the composite comprising said electron-donateive colorreactant, said electron-acceptive material and said electric conductivematerial is applied or impregnated into the base sheets.

When an electrode is contacted with a surface of the -composite of theelectro-sensitive recording medium and the electrode is connected with apositive pole and the base sheet is connected with a negative pole so asto impress a voltage on the recording medium, the portions of theelectron-donative color reactant and the electron-acceptive materialwhere the electric current passes through are reacted and colored.

We made some experments and examined on the coloring mechanism of thecomposite comprising said electron-donative color reactant, saidelectronacceptive material and said electric conductive material due tothe application of the electric current, and found many facts mentionedbelow.

When the electric current is applied to the compos ite, the humidity inthe composite causes the ionization of circumference of theelectron-donative color reactant and the electron-acceptive material,and then the color reactant constitutes the ionized or excited latentimage. The latent image is reacted with the electronacceptive materialso as to reveal itself and color itself. Alternatively, when thecomposite is heated, the electron-donative color reactant or/and theelectronacceptive material are melted and reacted with each other so asto color the reactant. Therefore, when the electric current is appliedto the composite and said composite is exothermically heated, the binderis softened or destroyed, or the electron-donative color reactant and/orthe electron-acceptive material are melted and reacted with each otherso as to color the color reactant.

It is desirable that an electrolyte is contained in the composite inorder to constitute a latent image of the eleetron-donative colorreactant ionized or activated by means of the application of theelectric current, but the volume of the electrolyte is not important. Avery small amount of water is needed to color the reactantelectroytically and the amount of the moisture produced in thehydrophilic binder under normal conditions is sufficient to color thereactant. A wetting agent such as glycerine and ethylene glycol may becontained in the composite to stabilize the moisture contained.

When the moisture contained is, however, too much,in spite of saidelectrolytic coloring being easily brough about. The coloring phenomenadue to the exothermical heating from the application of the electriccurrent does not readily occur and therefor the practical value of thefinished products is deteriorated. There are created the tackiness onthe surface of the electrosensitive recording medium, the colored andsmudged condition on the surface before the application of the electriccurrent and the deterioration of the preservability or wettness of therecording medium.

In case the electron-donative color reactant is electrolyzed in anelectrolyzed in an electrolyte solution, the coloring due to the anodicoxidation is brought only at the portion contacted with anode or at thevery proximate portion thereof.

According to the present invention, the electrolysis occurs between theelectron-donative color reactant and the electron-acceptive material.The coloring phenomena is brough about not only on the surface of theportions contacted with the anode but also within the interior portionof the current applied section, thus the density of coloring isconsiderably obstained.

In accordance with the present invention, the recording sensitivity isgood enough because of the coloring reaction being brought about as setforth due to the multiplex effect of exothermic and electrolyticphenomena and a visible recording image of clear and stable is obtainedby the electric signal.

EXAMPLE 1 1. preparation liquid A: crystal violet lacetone parts Thecomposite is added to 30 parts of polyvinyl alcohol 5 percent aqueoussolution, ground so as to make the size of the particles less than 3micron by means of ball mill to mix with the aqueous solution.

2. preparation of liquid B:

a. 4,4'-isopropylide ne diphenol 30 parts b. Kaoline 10 parts c. talcI60 parts d. polyvinyl alcohol 2 percent aqueous solution 500 parts e.latex 30 parts The composites of (a) and (b) respectively were added to(d). They were ground to make the size of the particles less than 3micron by a ball mill and then (c) and (e) were added to the groundcomposites and mixed enough with each other.

3. preparation of liquid'C:

The liquid A and B were mixed and lithium chloride percent aquueoussolution 30 parts and polymeric quaternary ammonium salt 20 percentaqueous solu- 1 tion 20 parts were added to the mixture. In this way,liquid C was prepared. i

4. Liquid C was applied and dried on a surface of an aluminum foil inorder to produce solid matter 8 g/m on the surface by using Meier bar,and the surface was humidity controlled in the air of relative humidity65 percent. A printing type electrode was pressed on the surface of theresultant recording medium and the aluminum foil was connected to thecathode and the printing type electrode was connected to the anode.Then, the voltage of 100v is impressed to the recording medium for 5millisecond. A clean blue image was formed on the portion of therecording medium contacted with the printing type electrode.

EXAMPLE 2 c. polyvinyl alcohol 4 percent aquueous solution 250 parts d.carboxy-methyl cellulose 2 percent aqueous solution 250 parts e. latex30 parts The composite (a) was added to (c) and both were ground untilthe particle size of them becomes less than 3 micron. (b), (d) and (e)were added to the resultant mixed solution and mixed all of them fully.

3. preparation of liquid C:

The liquid A and B were mixed, then sodium polyacrylate 40 percentaqueous solution 120 parts was mixed with the mixture so as to prepareliquid C.

4. Liquid C was applied and dried on the surface of an aluminum vacuumevaporated paper by means of Meier bar so as to produce the solid matterof 8 g/m on the surface.

The surface was humidity controlled in the air of relative humiditypercent. The recording medium prepared by the process mentioned abovewas wound around an aluminum cylinder so as to earth the aluminum vacuumevaporated surface of the recording medium through the aluminumcylinder. When a tangsten stylus having a diameter of l00 micron waspressed on the surface of the recording medium under the pressure of 10g and the voltage v was impressed on the tangsten stylus revoluting thecylinder at the circumferential speed of 1 meter per second, an alectriccurrent of about 1 milli ampere was flown and a clear red image wasobtained.

EXAMPLE 3 1. preparation of liquid A: a. S-diethylamino.7-dibenzylamino. S-methylfluoran 5 parts b. 3-diethylamino. 6-methyl.7-chlorofluuoran 3 parts c. benzoil-leucomethylene blue 4 parts d.rhodamine B lactum 2 parts The composites mentioned above was treated bythe similar way to Example l.

2. preparation of liquid B: liquid B was" prepared in simiilar way toExample 2.

3. preparation of liquid C: Liquid C was prepared in similar way toExample 2.

4. Aluminum vacuum evaporated Mylar film was employed as a base sheetand treated in similar way to Example 2 and a recording medium wasobtained. The recording medium was treated by recording process insimilar to Example 2 and a distinct and black image was formed.

EXAMPLE 4 1. preparation of liquid A: crystal violet lactone 10 partsThe lactone was added-to polyvinyl alcohol 5 percent aqueous solution 30parts and ground until the size of them become less than 3' micron bymeans of ball mill and then they were mixed.

2. preparation of liwuid B:

a. Kaolin 40 parts i b. talc 120 parts c. polyvinyl alcohol 3 percentaqueous solution 300 parts d. latex 30 parts The composites of (a) and(b) were ground enough until the size of them becomes less than 3 micronby a ball mill and the ground composite was added to the mixed solutionof (c) and (d) and they were mixed.

3. The mixed solution of liquid A and B were applied and dried on apaper of 30g of basic weight by Meier bar until the volume of solidmatter on the surface of the paper becomes 8g/m This paper was immersedinto lithium chloride 4 percent aqueous solution and dired in the air ofrelative humidity 65 percent. The paper prepared in this was was put onan aluminum plate with the applied face of the paper upward and furthera printing type electrode was placed on them and pressed. The aluminumplate was connected to the cathode and the electrode to the anode. Thevoltage of 120v was impressed on them for millisecond thereby obtained adistinct and blue image on the portion of the recording sheet contactedwith the printing type electrode.

EXAMPLE 5 l. preparation of liquid A:

All the said composites were treated in the same manner as Example 4 forpreparing liquid A.

'2. preparation of liquid B:

a. 4,4'-isopropyliden diphenol 60 parts b. talc 160 parts c.polyvinylalcohol 3 percent aqueous solution 30 parts The composite of(a) was added to (c) and ground sufficiently until the size of thembecomes less than 3 micron. (b) and (d) were added to the resultantground composite and they were mixed enough.

3. The mixed solution of liquid A and B were applied and dried on apaper of 30g of basic weight by Meier bar until the volume of solidmatter on the surface of the paper becomes lOg/m then the paper in thisway treated was immersed into sodium chloride 4 percent aqueous solutionand dried until the humidity contained of the recording sheet becomesabout 25 percent. The paper treated as mentioned above was put aroundthe aluminum cylinder and the tangsten stylus of diameter of 100 micronwas put on a surface of the recording sheet under the pressure of 10g.The aluminum cylinder was connected with the cathode, the stylus withthe anode and a voltage of 120 v was impressed on them revoluting thecylinder at the circumferential speed of 1 meter per second, therebyabout 2 milliampere of the electric current occured and a clean andblack image was obtained.

EXAMPLE 6 l. preparation of liquid A: a. 3-diethylamino.7-dibenzylamino. S-methylfluoran 5 parts b. 3-diethylamino. 6-methyl.7-chlorofluoran 3 parts c. rhodamine B lactum.. 2 parts All thecomposites mentioned above were treated in a similar manner to Example 4to prepare liquid A.

2. preparation of liquid B:

It was prepared in the same manner as Example 5.

3. preparation of liquid C:

Liquid A andB were mixed and ammonium chloride 10 percent aqueoussolution 100 parts and glycerine 10 parts were added, and they weremixed sufficiently.

4. Liquid C was applied on the surface of aluminum foil by Meier bar inorder to form solid matter lOg/m on the surface and the surface wasdried until the humidity in the liquid applied lay becomes about 25percent.

The recording medium prepared by the process mentioned above was treatedand recorded by the use of the voltage of v and 0.5 milliampere in asimilar manner to Example 5, thereby a distinct and black image wasobtained.

What we claim is 1. An electrical recording medium comprising acomposite mounted on a base sheet, said composite comprising anelectric-donative leuco compound, an electron-acceptive material and anelectrically conductive material, the electron-donative leuco compoundand the electron-acceptive material being dispersed in a hydrophilicbinder, and forming a color upon being reacted with each other saidreaction being brought about by applying an electric current to saidmedium.

2. An electrical recording medium as claimed in claim 1, wherein theelectrically conductive material is an electrolyte.

' 3. An electrical recording medium as claimed in claim 1, wherein thebase sheet is electrically conductive.

4. An electrical process for recording on an electrical recording mediumcomprising the steps of mounting a composite comprising anelectron-donative color reactant, an electron-acceptive material and anelectrically conductive material as defined in claim 1 upon a basesheet, applying an electric current to said recording medium therebyeffecting a reaction between the electron-donative color reactant andthe electronacceptive material and thereby coloring the color reactant.

2. An electrical recording medium as claimed in claim 1, wherein theelectrically conductive material is an electrolyte.
 3. An electricalrecording medium as claimed in claim 1, wherein the base sheet iselectrically conductive.
 4. An electrical process for recording on anelectrical recording medium comprising the steps of mounting a compositecomprising an electron-donative color reactant, an electron-acceptivematerial and an electrically conductive material as defined in claim 1upon a base sheet, applying an electric current to said recording mediumthereby effecting a reaction between the electron-donative colorreactant and the electron-acceptive material and thereby coloring thecolor reactant.